1 /*
2  * Copyright 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.hardware.display;
18 
19 import android.annotation.NonNull;
20 import android.annotation.Nullable;
21 import android.annotation.SystemApi;
22 import android.os.Parcel;
23 import android.os.Parcelable;
24 
25 import com.android.internal.util.Preconditions;
26 
27 import java.time.LocalDate;
28 import java.util.Arrays;
29 import java.util.Objects;
30 
31 /**
32  * AmbientBrightnessDayStats stores and manipulates brightness stats over a single day.
33  * {@see DisplayManager.getAmbientBrightnessStats()}
34  *
35  * @hide
36  */
37 @SystemApi
38 public final class AmbientBrightnessDayStats implements Parcelable {
39 
40     /** The localdate for which brightness stats are being tracked */
41     private final LocalDate mLocalDate;
42 
43     /** Ambient brightness values for creating bucket boundaries from */
44     private final float[] mBucketBoundaries;
45 
46     /** Stats of how much time (in seconds) was spent in each of the buckets */
47     private final float[] mStats;
48 
49     /**
50      * Initialize day stats from the given state. The time spent in each of the bucket is
51      * initialized to 0.
52      *
53      * @param localDate        The date for which stats are being tracked
54      * @param bucketBoundaries Bucket boundaries used from creating the buckets from
55      * @hide
56      */
AmbientBrightnessDayStats(@onNull LocalDate localDate, @NonNull float[] bucketBoundaries)57     public AmbientBrightnessDayStats(@NonNull LocalDate localDate,
58             @NonNull float[] bucketBoundaries) {
59         this(localDate, bucketBoundaries, null);
60     }
61 
62     /**
63      * Initialize day stats from the given state
64      *
65      * @param localDate        The date for which stats are being tracked
66      * @param bucketBoundaries Bucket boundaries used from creating the buckets from
67      * @param stats            Time spent in each of the buckets (in seconds)
68      * @hide
69      */
AmbientBrightnessDayStats(@onNull LocalDate localDate, @NonNull float[] bucketBoundaries, float[] stats)70     public AmbientBrightnessDayStats(@NonNull LocalDate localDate,
71             @NonNull float[] bucketBoundaries, float[] stats) {
72         Objects.requireNonNull(localDate);
73         Objects.requireNonNull(bucketBoundaries);
74         Preconditions.checkArrayElementsInRange(bucketBoundaries, 0, Float.MAX_VALUE,
75                 "bucketBoundaries");
76         if (bucketBoundaries.length < 1) {
77             throw new IllegalArgumentException("Bucket boundaries must contain at least 1 value");
78         }
79         checkSorted(bucketBoundaries);
80         if (stats == null) {
81             stats = new float[bucketBoundaries.length];
82         } else {
83             Preconditions.checkArrayElementsInRange(stats, 0, Float.MAX_VALUE, "stats");
84             if (bucketBoundaries.length != stats.length) {
85                 throw new IllegalArgumentException(
86                         "Bucket boundaries and stats must be of same size.");
87             }
88         }
89         mLocalDate = localDate;
90         mBucketBoundaries = bucketBoundaries;
91         mStats = stats;
92     }
93 
94     /**
95      * @return The {@link LocalDate} for which brightness stats are being tracked.
96      */
getLocalDate()97     public LocalDate getLocalDate() {
98         return mLocalDate;
99     }
100 
101     /**
102      * @return Aggregated stats of time spent (in seconds) in various buckets.
103      */
getStats()104     public float[] getStats() {
105         return mStats;
106     }
107 
108     /**
109      * Returns the bucket boundaries (in lux) used for creating buckets. For eg., if the bucket
110      * boundaries array is {b1, b2, b3}, the buckets will be [b1, b2), [b2, b3), [b3, inf).
111      *
112      * @return The list of bucket boundaries.
113      */
getBucketBoundaries()114     public float[] getBucketBoundaries() {
115         return mBucketBoundaries;
116     }
117 
AmbientBrightnessDayStats(Parcel source)118     private AmbientBrightnessDayStats(Parcel source) {
119         mLocalDate = LocalDate.parse(source.readString());
120         mBucketBoundaries = source.createFloatArray();
121         mStats = source.createFloatArray();
122     }
123 
124     public static final @android.annotation.NonNull Creator<AmbientBrightnessDayStats> CREATOR =
125             new Creator<AmbientBrightnessDayStats>() {
126 
127                 @Override
128                 public AmbientBrightnessDayStats createFromParcel(Parcel source) {
129                     return new AmbientBrightnessDayStats(source);
130                 }
131 
132                 @Override
133                 public AmbientBrightnessDayStats[] newArray(int size) {
134                     return new AmbientBrightnessDayStats[size];
135                 }
136             };
137 
138     @Override
equals(@ullable Object obj)139     public boolean equals(@Nullable Object obj) {
140         if (this == obj) {
141             return true;
142         }
143         if (obj == null) {
144             return false;
145         }
146         if (getClass() != obj.getClass()) {
147             return false;
148         }
149         AmbientBrightnessDayStats other = (AmbientBrightnessDayStats) obj;
150         return mLocalDate.equals(other.mLocalDate) && Arrays.equals(mBucketBoundaries,
151                 other.mBucketBoundaries) && Arrays.equals(mStats, other.mStats);
152     }
153 
154     @Override
hashCode()155     public int hashCode() {
156         final int prime = 31;
157         int result = 1;
158         result = result * prime + mLocalDate.hashCode();
159         result = result * prime + Arrays.hashCode(mBucketBoundaries);
160         result = result * prime + Arrays.hashCode(mStats);
161         return result;
162     }
163 
164     @NonNull
165     @Override
toString()166     public String toString() {
167         StringBuilder bucketBoundariesString = new StringBuilder();
168         StringBuilder statsString = new StringBuilder();
169         for (int i = 0; i < mBucketBoundaries.length; i++) {
170             if (i != 0) {
171                 bucketBoundariesString.append(", ");
172                 statsString.append(", ");
173             }
174             bucketBoundariesString.append(mBucketBoundaries[i]);
175             statsString.append(mStats[i]);
176         }
177         return new StringBuilder()
178                 .append(mLocalDate).append(" ")
179                 .append("{").append(bucketBoundariesString).append("} ")
180                 .append("{").append(statsString).append("}").toString();
181     }
182 
183     @Override
describeContents()184     public int describeContents() {
185         return 0;
186     }
187 
188     @Override
writeToParcel(Parcel dest, int flags)189     public void writeToParcel(Parcel dest, int flags) {
190         dest.writeString(mLocalDate.toString());
191         dest.writeFloatArray(mBucketBoundaries);
192         dest.writeFloatArray(mStats);
193     }
194 
195     /**
196      * Updates the stats by incrementing the time spent for the appropriate bucket based on ambient
197      * brightness reading.
198      *
199      * @param ambientBrightness Ambient brightness reading (in lux)
200      * @param durationSec       Time spent with the given reading (in seconds)
201      * @hide
202      */
log(float ambientBrightness, float durationSec)203     public void log(float ambientBrightness, float durationSec) {
204         int bucketIndex = getBucketIndex(ambientBrightness);
205         if (bucketIndex >= 0) {
206             mStats[bucketIndex] += durationSec;
207         }
208     }
209 
getBucketIndex(float ambientBrightness)210     private int getBucketIndex(float ambientBrightness) {
211         if (ambientBrightness < mBucketBoundaries[0] || Float.isNaN(ambientBrightness)) {
212             return -1;
213         }
214         int low = 0;
215         int high = mBucketBoundaries.length - 1;
216         while (low < high) {
217             int mid = (low + high) / 2;
218             if (mBucketBoundaries[mid] <= ambientBrightness
219                     && ambientBrightness < mBucketBoundaries[mid + 1]) {
220                 return mid;
221             } else if (mBucketBoundaries[mid] < ambientBrightness) {
222                 low = mid + 1;
223             } else if (mBucketBoundaries[mid] > ambientBrightness) {
224                 high = mid - 1;
225             }
226         }
227         return low;
228     }
229 
checkSorted(float[] values)230     private static void checkSorted(float[] values) {
231         if (values.length <= 1) {
232             return;
233         }
234         float prevValue = values[0];
235         for (int i = 1; i < values.length; i++) {
236             Preconditions.checkState(prevValue < values[i]);
237             prevValue = values[i];
238         }
239         return;
240     }
241 }
242